Thermal and moisture resistant insulative sheet

ABSTRACT

A composite bubble-pack assembly comprising (i) a first bubble-pack having a first thermoplastic film having a plurality of portions wherein each of the portions defines a cavity and a second thermoplastic film in sealed engagement with the first film to provide a plurality of closed cavities; (ii) a second bubble-pack having a third thermoplastic film having a plurality of portions wherein each of the portions defines a cavity, and a fourth thermoplastic film in sealed engagement with the third film to provide a plurality of closed cavities; (iii) and a film selected from the group consisting of a thin foil of metal or a metallized thermoplastic film interposed between and bonded to the first bubble-pack and the second bubble-pack.

FIELD OF THE INVENTION

[0001] This invention relates to bubble-pack thermal and moistureresistant insulation materials for use in the construction of buildings,roads, septic fields, aircraft runways and the like.

BACKGROUND TO THE INVENTION

[0002] It is well known to use separating sheets of materials tothermally separate construction materials from underground soils. Thesematerials are also used to hold and retain the different layers of sandand rocks used in the construction of roads which under the repetitiveaction of freeze and thaw leads to cracks and holes in the exposedexternal layer of the roads. These materials are also used as moisturebarriers in buildings under construction, especially underneath theconcrete floor of the basement that otherwise would be directly incontact with the soil and the moisture.

[0003] However, the aforesaid materials are generally formed as rigid orsemi-rigid insulating panels which have a strong tendency to crack andbreak apart under heavy loads which, thus decreases their efficacy.Furthermore, they are difficult to install and are limited in sizebecause of transportation problems.

[0004] Further, although, these materials are made in such a way thatthey do not transfer heat by conduction or convection, they generallyhave a relatively high reflective surface material that still allowsradiation heat transfer that is fairly significant for large surfaces.

[0005] Insulation materials are also know which comprise a clean,non-toxic, heat barrier made of aluminum foil bonded to a single ordouble layer of polyethylene-formed bubbles spaced one bubble fromanother bubble in the so-called “bubble-pack” arrangement. Non-foilbubble-packs are used extensively as packaging material, whereas themetal foil bubble-pack sheet is used as thermal insulation in wood framestructures, walls, attics, crawl spaces, basements and the like and aswrapping for hot water heaters, hot and cold water pipes, air ducts andthe like. The reflective surface of the metal, particularly, aluminumfoil enhances the thermal insulation of the air-containing bubble-pack.

[0006] Generally, low density polyethylene films of 1-12 mil,optionally, with various amounts of linear low density polyethylene inadmixture when additional strength is required, are used for the aboveapplications. The insulating properties of the bubble pack primarilyarise from the air in the voids. Typically, bubble diameters of 1.25 cm,0.60 cm and 0.45 cm are selected.

[0007] In certain environments, the aluminum foil of the prior artassemblies are vulnerable to chemical attack or delamination from thethermoplastic film by reason of being exposed to detrimental chemicals,acidic or alkaline vapours or the like.

[0008] Further, to reduce the risk of such undesired chemical attackand, also, to utilize the radiative insulative property of the aluminumsurface, a space or gap is left between the prior art assembly and thewall, strut and the like adjacent the assembly. This results in arelatively larger combined unit than would otherwise be desired.

[0009] There is, therefore a need for a thermal and moisture resistant,insulation pack for use in road and building construction that is of asimple form, low cost to manufacture which is flexible, easy to carryand apply, provides reduced radiative heat transfer and provides reducedtotal unit construction volume.

SUMMARY OF THE INVENTION

[0010] It is an object of the present invention to provide an enhancedthermal and moisture resistant insulation sheet for use in road andbuilding construction that is sufficiently flexible as to be readilyadapted to be carried, installed and enhanced weight resistant.

[0011] It is a further object to provide a thermal and moistureinsulation sheet which is environmentally more stable to attack on themetal and delamination.

[0012] It is a further object to provide a thermal and moistureresistant insulative sheet for use in abutement with an adjacent wall,strut and the like to provide an insulative barrier system of reducedthickness.

[0013] Accordingly, in one aspect, the invention provides a compositebubble-pack assembly comprising (i) a first bubble-pack having a firstthermoplastic film having a plurality of portions wherein each of saidportions defines a cavity and a second thermoplastic film in sealedengagement with said first film to provide a plurality of closed saidcavities; (ii) a second bubble-pack having a third thermoplastic filmhaving a plurality of portions wherein each of said portions defines acavity and a fourth thermoplastic film in sealed engagement with saidthird film to provide a plurality of closed said cavities; and (iii) afilm selected from the group consisting of a thin foil of metal or ametallized thermoplastic film interposed between and bonded to saidfirst bubble-pack and said second bubble-pack.

[0014] The terms “cavity” or “cavities” in this specification includevoids, bubbles or other like closed spaces. The cavities may be formedof any desired suitable shape, such as, for example, of asemi-cylindrical, oblong or rectangular form. However, a generallyhemi-spherical cavity is preferred.

[0015] The number, size and layout of the bubble in the pack accordingto the invention may be readily selected, determined and manufactured bythe skilled artisan. Typically, in a single pack, the bubbles arearrayed in a coplanar off-set arrangement. Each of the hemi-sphericalbubbles may be of any suitable diameter and height protruding out of theplane of the bonded films. Typically, the bubble has a diameter selectedfrom 0.5 cm-5 cm, preferably 0.8-1.5 cm; and a height selected from 0.2cm-1 cm, preferably 0.4 cm-0.6 cm. A preferred bubble-pack has an arrayof about 400 bubble per 900 cm².

[0016] The thermoplastic films may be formed of any suitable polymer orcopolymer. The first, second, third and fourth films may be formed ofthe same or different material. Most preferably, the assembly has eachof the thermoplastic films formed of a polyethylene or a nylon. A mostpreferred plastic is polyethylene, particularly a low-densitypolyethylene, optionally, in admixture with a linear low densitypolyethylene of use as aforesaid first and second films.

[0017] The composite assembly of the invention further comprises one ormore foils, layers, films, laminates or the like of a suitable metal,for example, aluminum or a metallized thermoplastic film within theassembly to enhance reflection of infra-red radiation.

[0018] Preferably, the aluminum foil forms part of the laminate havingthe foil heat sealed between a pair of polyethylene films to provide abetter seal to the pair of bubble arrays.

[0019] The composite bubble-pack assembly according to the invention isof particular value when used in an environment that has a detrimentaleffect on the exposed metal when the latter is used as an outer film onbubble packs according to the prior art. Since, in the presentinvention, the metal is, in effect, embedded in a doublethermoplastic-air-filled void system, it is remote from metal-attachingchemicals or an environment which effects metal-thermoplastic filmdelamination.

[0020] Further, I have found that in order for the metal foil to beefficacious in providing reflective heat reduction when bonded as anouter film, there needs to be a gap or space between the metal foil andadjacent wall, ground or like member. This, thus, often results in athicker than desired insulative assembly. In contrast, the compositeassembly according to the invention has an inherently built-in air spaceadjacent each side of the metal foil to provide the desired reflectiveproperty. This, thus, offers a more compact fully insulative package,sheet and the like than the prior art.

[0021] Thus, the assembly according to the invention comprises aninsulative sheet that provides air spaces on both sides of a metal ormetallized foil which provides thermal and moisture insulationenhancement to the assembly and physical protection to the foil, in therough and tough environment of placement adjacent to concrete, soil andother natural ground conditions, comprising particulate matter such asgravel and lime.

[0022] The sheet according to the invention is flexible and easy toapply to cover objects of a plurality of shapes.

[0023] The sheet effects useful reduction of heat transfer in each ofthe conduction, convection and radiation modes, notwithstanding therelative thinness of the sheet.

[0024] Further, the metal foil is protected from direct attack by mostchemical agents that do not attack the thermoplastic layers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order that the invention may be better understood, preferredembodiments will now be described by way of example only, with referenceto the accompanying drawings, wherein

[0026]FIG. 1 is an isometric view of an insulation panel comprising abubble-pack assembly according to the prior art;

[0027]FIG. 2 is a diagrammatic top plan view of an embodiment insulationpanel comprising a bubble-pack assembly according to the invention;

[0028]FIG. 3 is a diagrammatic enlarged sectional view taken along theline 3-3 of FIG. 2;

[0029]FIG. 4 is a schematic sectional view of an alternative embodimentaccording to the invention; and wherein the same numerals denote likeparts.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] With reference to FIG. 1, this show generally as 10, a doublelayer, bubble-pack with aluminum foil insulation assembly according tothe prior art. The double layer consists of a pair of bubble arrays 12,14 bonded together through an intervening low density polyethylene film16. Arrays, 12, 14 are formed of a plurality of bubble or sealedcavities 18, 20, respectively, from a 5 mil polyethylene film 22, 24,respectively. Each of films 22, 24 at their outer surfaces is bonded toa reflective aluminum foil 26, 28, respectively, to provide the wholeassembly with external aluminum surfaces.

[0031] Assembly 10 has approximately twenty, 1 cm diameter, 0.5 cm highbubbles per 30 cm length and breadth within each of films 22, 24.

[0032] The aforesaid assembly 10 is made by a double hot roller thermaland vacuum forming process for cavity forming and lamination sealingtechniques known in the art.

[0033] With reference to FIGS. 2 and 3, these show generally as 100 acomposite double bubble-pack assembly according to the invention, havingan aluminum foil 102 disposed between and bonded to bubble arrays 112and 114 formed as for prior art FIG. 1 assembly. Bubbles 118 and 120 areencapsulated between polyethylene films 116 and 128.

[0034] Aluminum foil 102 has a low emissivity value of less than 5% oneach surface to essentially eliminate heat transfer by radiation.

[0035] Each of the single bubble-pack layers 112, 114 provides boththermal conduction and convection insulation, and, in combination withthe aluminum surfaces, excellent radiation insulation.

[0036] The composite bubble-pack 100 offers significant resistance toheavy loading whereby appreciative non-breakage of the air bubbles isoften found. Preferably, outer layers 128 are made slightly thicker thaninner layers 116 to better resist abrasion. Additional water resistanceor abrasion resistant films may be bonded or formed laminated to layer128. Such resultant composite bubble-pack assemblies are of particularuse in the construction of roads, septic fields, aircraft runways andthe like.

[0037] Further, in consequence that composite assemblies of theinvention have better thermal R-values than prior art assemblies,thinner or higher insulative assemblies may be provided. Thinnerassemblies, say 0.2 cm-0.8 cm thick facilitate the manufacture,transportation and handling of rolls of different desired sizes.

[0038] In alternative embodiments, but still illustrated by FIGS. 2 and3, metal foil 102 is substituted with a strong and resistant plastics ofa very thin, preferably a few hundred angstroms (1 angstrom equals 10⁻¹⁰m), layer of metallic deposition on each side to provide the lowemissivity surfaces.

[0039]FIG. 4 shows a similar embodiment to that of FIG. 3 wherein foil102 is laminated by heat sealing between a pair of 2 mil polyethylenefilms 130 and 132 between bubble arrays 12, 14, at one of films 16.

[0040] Although this disclosure has described and illustrated certainpreferred embodiments of the invention, it is to be understood that theinvention is not restricted to those particular embodiments. Rather, theinvention includes all embodiments which are functional or mechanicalequivalents of the specific embodiments and features that have beendescribed and illustrated.

1. A composite bubble-pack assembly comprising (i) a first bubble-packhaving a first thermoplastic film having a plurality of portions whereineach of said portions defines a cavity and a second thermoplastic filmin sealed engagement with said first film to provide a plurality ofclosed said cavities; (ii) a second bubble-pack having a thirdthermoplastic film having a plurality of portions wherein each of saidportions defines a cavity and a fourth thermoplastic film in sealedengagement with said third film to provide a plurality of closed saidcavities; and (iii) a film selected from the group consisting of a thinfoil of metal or a metallized thermoplastic film interposed between andbonded to said first bubble-pack and said second bubble-pack.
 2. Acomposite bubble-pack as defined in claim 1 wherein said metal ormetallized thermoplastic is a laminate layer interposed between a pairof polyethylene films to constitute a laminate interposed between andbonded to said first bubble-pack and said second bubble-pack.
 3. Acomposite bubble-pack assembly as defined in claim 1 wherein said metalis aluminum.
 4. A composite bubble-pack assembly as defined in claim 1wherein a least one of said first, second, third and fourth films isformed of a thermoplastic selected from the group consisting of a lowdensity polyethylene, a linear low density polyethylene and a nylon. 5.A composite bubble-pack assembly as defined in claim 1 having athickness selected from 0.4 cm to 1.2 cm.